• Precipitation helped drive distribution

    From ScienceDaily@1:317/3 to All on Monday, May 02, 2022 22:30:40
    Precipitation helped drive distribution of Alaska dinosaurs

    Date:
    May 2, 2022
    Source:
    University of Alaska Fairbanks
    Summary:
    Precipitation more than temperature influenced the distribution
    of herbivorous dinosaurs in what is now Alaska, according to
    new research.

    The finding discusses the distribution of hadrosaurids and
    ceratopsids - - the megaherbivores of the Late Cretaceous Period,
    100.5 million to 66 million years ago.



    FULL STORY ========================================================================== Precipitation more than temperature influenced the distribution of
    herbivorous dinosaurs in what is now Alaska, according to new research published this month.


    ==========================================================================
    The finding, published April 2 in the journal Geosciences, discusses
    the distribution of hadrosaurids and ceratopsids -- the megaherbivores
    of the Late Cretaceous Period, 100.5 million to 66 million years ago.

    The work can help scientists project what the Arctic region might look
    like in the years ahead if the climate turns similarly warm and wet.

    University of Alaska Fairbanks Geophysical Institute geology professor
    Paul McCarthy, who is also chair of the UAF Department of Geosciences, is co-author of the research paper written by Anthony Fiorillo of Southern Methodist University in Texas. McCarthy has been studying the region's
    ancient past for many years.

    "The reason we've been looking at Cretaceous environments up here is
    because Earth was in a greenhouse state at that point in time, and it
    offers the potential to provide analogs to what we might see, eventually,
    if global warming continues," McCarthy said.

    "We can't simulate the rates of change, which are likely to have been
    totally different in the Cretaceous," he said. "But we can simulate
    what an ice-free coast would look like and also see how rivers and
    floodplains would respond to spring snowmelt from the mountains if
    everything's not frozen. And we can look at the distribution of plants
    and animals." McCarthy, a sedimentologist and a fossil soils specialist,
    led the analysis of the depositional environments and ancient soils of
    three rock formations: the fossil-rich Prince Creek Formation along the Colville River in northern Alaska, the Lower Cantwell Formation in the
    Central Alaska Range and the Chignik Formation on the Alaska Peninsula.



    ==========================================================================
    The three formations are close enough to one another on the geologic
    time scale to allow for a climate comparison, according to the research
    paper. They all contain Late Cretaceous rocks that were deposited
    approximately 83 million to 66 million years ago.

    Fossilized plants and animals and ancient footprints get most of the
    public attention, but fossil soil has equally important information to
    offer through its preserved features, mineral composition and chemical
    makeup.

    "We can look at microscopic features preserved in the fossil soil
    samples and relate that to modern soil types to get an idea of where they formed," McCarthy said. "Are we looking at deserts? Are we looking at
    tropical rainforest or temperate forest? Or grasslands?" "Fossil soil
    also preserves pollen grains that can tell us something about the
    composition of the local vegetation," he said. "And it contains clay
    minerals, organic matter and the iron-carbonate mineral siderite, all
    of which can be used to determine precipitation and temperature using
    stable isotopic methods." From that, paleontologists can learn about
    the distribution of Alaska's dinosaurs.



    ========================================================================== Through analysis at UAF and elsewhere, scientists studying the three
    Alaska formations found a correlation between the amount of precipitation
    and the distribution of hadrosaurids and ceratopsids. They also found
    a lesser correlation between temperature and the distribution of those
    two groups of dinosaurs.

    Hadrosaurids, the duck-billed family of dinosaurs, preferred climates
    that were wetter and had a narrower annual temperature range. Adults
    weighed about 3 tons and reached about 30 feet in length. Their percentage dominance over the ceratopsids in the three studied formations increased
    in the more-favorable climate.

    Ceratopsids, a family with beaks and horns, preferred a milder and drier climate but never became dominant in percentage over the hadrosaurids in
    the three formations. Triceratops is perhaps the best known ceratopsid,
    at a length of about 25 to 30 feet and weighing 4.5 to 5.5 tons.

    The finding for greater influence of precipitation than temperature
    was based in part on prior research that looked at dinosaur teeth
    from the Prince Creek Formation, including teeth of hadrosaurids and ceratopsids. That study was led by Celina A. Suarez of the University
    of Arkansas and included work by McCarthy.

    Results from that dental study, authors of the new paper write, suggest
    that ceratopsids preferred the drier, better-drained regions of the
    Late Cretaceous Arctic landscape and that hadrosaurids preferred wetter
    regions of the landscape.

    Others involved in the Geosciences paper include Yoshitsugu Kobayashi
    of the Hokkaido University Museum at Hokkaido University in Japan and
    Marina B. Suarez of the University of Kansas.


    ========================================================================== Story Source: Materials provided by
    University_of_Alaska_Fairbanks. Original written by Rod Boyce. Note:
    Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Anthony R. Fiorillo, Paul J. McCarthy, Yoshitsugu Kobayashi,
    Marina B.

    Suarez. Cretaceous Dinosaurs across Alaska Show the Role
    of Paleoclimate in Structuring Ancient Large-Herbivore
    Populations. Geosciences, 2022; 12 (4): 161 DOI:
    10.3390/geosciences12040161 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/05/220502170938.htm

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